1. Field
Embodiments of the invention relate to electronic systems, and in particular, to radio frequency (RF) electronics.
2. Description of the Related Technology
RF power amplifiers can be used to boost the power of a RF signal having a relatively low power. Thereafter, the boosted RF signal can be used for a variety of purposes, included driving the antenna of a transmitter.
Power amplifiers can be included in mobile phones to amplify a RF signal for transmission. For example, in mobile phones having a time division multiple access (TDMA) architecture, such as those found in Global System for Mobile Communications (GSM), code division multiple access (CDMA), and wideband code division multiple access (W-CDMA) systems, a power amplifier can be used to amplify a RF signal. It can be important manage the amplification of a RF signal, as a desired transmit power level can depend on how far the user is away from a base station and/or the mobile environment. Power amplifiers can also be employed to aid in regulating the power level of the RF signal over time, so as to prevent signal interference from transmission during an assigned receive time slot.
The power consumption of a power amplifier can be an important consideration. One technique for reducing power consumption of a power amplifier is envelope tracking, in which the voltage level of the power supply of the power amplifier is changed in relation to the envelope of the RF signal. For example, when the envelope of the RF signal increases the voltage level of the power amplifier's power supply can be increased. Likewise, when the envelope of the RF signal decreases the voltage level of the power amplifier's power supply can be decreased to reduce power consumption.
There is a need for improved power amplifiers. Furthermore, there is a need for reducing capacitance in power amplifier systems. Moreover there is a need for an envelope tracker having a reduced capacitive load.